Aircraft are commonly equipped with Flight Management Systems (FMSs), which automate flight planning and other navigational tasks to reduce pilot workload. One such task is the calculation of an optimal vertical descent profile for reference during approach and landing. The FMS-computed vertical descent profile is ideally closely flown by a pilot such that the aircraft arrives at a desired horizontal (ground) distance ahead of its destination runway in an appropriate energy state; that is, at an altitude (commonly expressed as “Height Above Threshold”) and airspeed allowing adequate dissipation of the aircraft energy content during final approach, touchdown, and rollout. To facilitate adherence with the FMS-computed vertical descent profile, avionic display systems commonly present the pilot with a graphical depiction of the vertical descent profile on a two dimensional (2D) avionic display, which is seen from a vertically-oriented perspective and which is commonly referred to as a “Vertical Navigation (VNAV) display” or a “Vertical Situation Display (VSD).” In addition to providing graphics representative of the FMS-computed vertical descent profile, the VSD also includes symbology indicative the current vertical aircraft position, runway ground level, and other pertinent flight parameters.
Even when afforded the assistance of a well-designed VSD, pilots may find it difficult to follow an FMS-computed vertical descent profile under actual or “real world” flight conditions. Any combination of dynamic factors can result in significant deviations from the FMS-computed vertical descent profile including rapidly shifting wind conditions, excessive aircraft instability, delay in implementation of high-lift configuration extensions, and tactical interventions by Air Traffic Control (ATC), to list but a few examples. Deviations from the FMS-computed vertical descent profile can contribute to undesired penalties in fuel consumption, operational costs, and noise emissions, as well as an increased likelihood of unstable approaches, hard landings, and go around procedures potentially exacerbating air traffic congestion. While not all deviations from the FMS-generated vertical descent profile are avoidable, an appreciable number of such deviations are avoidable and occur nevertheless due to various contributing factors. Such contributes factors may include pilot difficulty in anticipating excessive aircraft instability during approach and descent due to adverse weather conditions, rapidly changing weather conditions, and/or last moment landing parameter changes.
There thus exists an ongoing need for avionic display systems and methods, which generate symbology useful in decreasing aircraft deviations from computed vertical descent profiles during approach and landing. Ideally, embodiments of such avionic display systems and methods would enhance pilot awareness and decision-making with respect to the anticipated occurrence and avoidance of aircraft instability during approach and landing. Other desirable features and characteristics of the present invention will become apparent from the subsequent Detailed Description and the appended Claims, taken in conjunction with the accompanying Drawings and the foregoing Background.